Keyboard locking device

ABSTRACT

A control mechanism in a keyboard of a data terminal device in which a key lock, when manually rotated in one direction, will selectively lock out one of a number of control keys on a keyboard, and when rotated in the opposite direction, will selectively lock out others of the remaining control keys. Both lock out conditions are released by the energizing of a solenoid at the end of a machine operation. A second solenoid energized upon the initiation of a machine operation locks the control keys in their operated position during the machine operation.

United States Patent I Ikeda [s41 KEYBOARD LOCKING DEVICE [72] lnventorz Kazuhiko Ikeda, Tokyo, Japan 73 Assignee: The National Cash Register company, Dayton, Ohio [22] Filed: Sept. 1, 1971 [21] Appl. No.: 177,005

[52] US. Cl ..235/26, 235/27, 2 35/l30 R [51] Int. Cl 25/00, G07g H00 [58] Field of Search..235/26, 27, 130 R, 60.49, 62 F,

[56] References Cited UNITED STATES PATENTS 8/1940 Colley etal .Q ..235/26 4/ 1942 Kelly ..235/27 [451 N6v. 2 s, 1972 9/1969 Busch ....'......235/l30 R 6/1970 Taylor et al. ..235/27 Primary Examiner-Stephen J. Tomsky Attorney-LT. Cavender et al.

[57] ABSTRACT A control mechanism in a keyboard of a data terminal device in which a key lock, when manually rotated in one direction, will selectively lock out one of a number of control keys on a keyboard, and when rotated in'the opposite direction, will selectively lock out others of the remaining control keys. Both lock out conditions are released by the energizing of a solenoid at the end of a machine operation. A second solenoid energized upon the initiation of a machine operation locks the control keys in their operated position during the machine operation.

'13Claims,3DrawingFigures PATENTEDNHV28I97Z 3.703.987 SHEET20F3 KAZUHIKO IKEDA ms- ATTORNEYS.

' INVENTOR PATENTED um 28 1912' INVENTOR HIKO IKEDA HlS ATTORNEYS KEYBOARD LOCKING DEVICE BACKGROUND OF INVENTION The present invention is'directed to the keyboard of an electronically operated cash register containing control'keys which function, when depressed, to establish electronic circuits for performing various operations associated with the cash register such as the entry of amounts of money, the addition of a plurality of entries, printing of the amounts entered, and restoring the device to a condition to accept a new series of operations. It is desirable that. only one control key be operated at one time, less confusion arises in the operation of the device. It is further desirable to lock the keys in their position during a machine operation and to condition the return of the control key that has been operated to its home position at the completion of the operation of the device. I I

SUMMARY or THE INVENTION It is an object of this invention to provide a manuallyoperated control mechanism capable of alternately selecting a predetermined number of control keys for operation. It is another object of this invention to provide a mechanism which will hold a control key in an operating position until the machine operation is completed.

In carrying out these objects, there is provided a locking device associated with a plurality of control keys which includes a pair of slidably mounted locking detents, a drive member and an arm member actuated by a lock cylinder to selectively position the locking detents to lock various control keys in position, a second arm member adapted to hold one of said locking detents in a blocking position, and a pair of solenoids selectively controlling said second arm member to disable the operation of one of the locking detents after a machine operation has been initiated and to release said locking detent after the machine operation has been completed. I

The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the keyboard of the present embodiment.

FIG. 2 is a partial detailed side view of the keyboard showing the control keys and the locking mechanism.

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2, showing the solenoids for controlling the operation of the locking mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION .Referring now to FIG. 1, there is shown a view of the keyboard 20 used in the electronic cash register of the present embodiment. Included in the keyboard are a row of control keys 21, a row of clerk keys 22, two rows of transaction keys 23, three rows of amount keys24, and two rows of address-keys 25. The present invention is directed to a locking mechanism which is utilized with the row of control keys 21, which includes a register key 26, a read key 27, and a reset key 28. The register key 26 functions to condition the cash register for various machine operations controlled bythekeys in the transaction row 23, the read key 27 functions to read data inserted in the cash register, and the reset key 28 functions, whendepressed, to erase all the information inserted in the cash register and to return all the depressed keys to their home position.

Mounted adjacent the control keys is a key lock cylinder 30, which is operated by inserting a key and then rotating the lock cylinder clockwise or counterclockwise. As will be described more fully hereinafter,

rotation of the key lock cylinder 30 in a clock-wise direction will disable the reset key 26 from being depressed while a counter-clockwise rotation of the lock will condition only the reset key for operation.

Referring now to FIG. 2, there is shown slidably mounted, within the top frame member 31 of the keyboard 20, the three control keys 26 to 28 inclusive. Each of the keys are urged into their upward or home position by a spring 32, mounted between a stud 33 located on the key member and a portion of the keyboard. The stem portion of each of the key members comprises a hook portion 34 and a rod portion 35 positioned within slots located in a locking detent member 36 slidably mounted on a pair of support members 37, 38. As shown' in FIG. 3, the detent member 36 has a bent over flange portion 39 containing a slotted portion 40 on which is mounted a compression spring 41 positioned between the support member 38 and the detent member 36. The spring 41 normally urges the detent member 36 to the left as viewed in FIGS. 2 and 3. The detent member 36 contains a plurality of slots 42 which allows the solid portion 43 (FIG. 2) between the slots to cooperate with the'hook portions 34 of the keys 26 to 28 inclusive, whereby the detent member 36 will be moved to the right upon depression of one of the control keys, as will be described more fully hereinafter.

Slidably'mounted on the support members 37, 38, is a blocking detent member 44 having a bent-over flange 45 with a slotted portion 46 supporting a compression spring 47 mounted between the support member 37 and the detent member 44, and which normally urges the detent member 44 to the right, as shown in FIGS. 2 and 3. Located in the detent number are a series of slots 48 which cooperate with the rod portions 35 of the .keys 26 to 28 inclusive, which will be described more fully hereinafter.

As shown in FIG. I, mounted on the keyboard adjacent the keys 26 to 28 inclusive, is the lock cylinder 30 which has a stud 50 (FIG. 2) depending from the bottom of the cylinder. The stud 50 is positioned within a slot 51 located in a control plate 52 which is'slidably mounted on three studs 53 secured to the framework of the machine. The studs 53 are positionedTwithin slots 54 located in the control plate 52. The front portion of the control plate 52 comprises a bent-over flange 55 (FIG. 2) which is positioned adjacent the blocking detent 44. The spring 47 engaging the detent 44 normally urges the detent into engagement with the flange 55. A spring-56 which is mounted between the control plate 52 and a portion of the machine framework (not as shown in FIGS. 2 and 3.

Rotatably mounted on a pin 57 located adjacent the control plate 52 is an arm member 58 and a bell crank 60. Mounted on one end of the arm 58 is a roller 61,

while the other end of the arm has a shoulder 62 which i normally engages the end of the flange portion 39 of the detent member 36. A spring 63 mounted between a stud 64 and the arm 58 urges the arm in a clockwise direction about the pin 57. This movement will move the roller 61 into engagement with a cam surface 65 of i the control plate 52 and will also move the shoulder 62 into a blocking engagement with the detent 36.

The bell crank 60 has a shoulder portion 66 which is moved into a blocking engagement with detent 36 by a spring 67 mounted between the bell crank and a stud 68. The bell crank has a pair of arm portions .70, 71. The arm portion 70 has a depending shoulder 72 which engages an armature member 73 of a solenoid 74. The arm portion 71 has a depending shoulder 75 which engages a shoulder portion 76 of a latch member 77 rotatably mounted on a pin 78 secured in the machine framework. The other end of the latch member 77 engages an armature 80 of a solenoid 81. A spring 82 mounted between the latch 77 and the stud 68 normally urges the latch member in a clockwise direction as viewed in FIG. 3.

Prior to the operation of the machine, the control.

plate 52 will be in the position shown in FIG. 3 due to the action of spring 56. The locking detent 36 will be held by the arm 58 and bell crank 62 from moving to the right as viewed in FIG. 3. This condition will prevent any of the keys 26 to 28 inclusive from being depressed since the solid portions 43 of the detent 36 will block the hook portions 34 of the key from movement in a downward direction. The detent 44 will also be positioned by the spring 47, to block the movement of the rod portion 35 of the keys in a downward direction. Thus the key members 26 to 28 inclusive are disabled from movement by both detents 36, 44. If a re gister or read operation is tooccur, the owner will insert a key in the key cylinder 30 and rotate the cylinder 90 in a clockwise direction as viewed in' FIGS. 1 and 3. Clockwise movement of the cylinder 30 will move the stud 50 to the position 83 (FIG. 3), thereby moving the control plate 52 a predetermined distance to the left as viewed in FIG. 3. This movement of the plate'52 will move the blocking detent 44 to the left an equal distance due to the engagement of the detent by the flange 55 of the control plate 52, thereby allowing the control keys 26 and 27 to be depressed while disabling the control key 28 from being depressed. Thus the register key 26 (FIG. 1) and the read key 27 are conditioned for operation while thereset key 28 is not.

At the start of a machine operation, the solenoid 74 will have been energized, thus rotating the armature member 73 in a clockwise direction. This action will rotate the bell crank 70 counter-clockwise, thus removing its shoulder 66 from a blocking position with the detent 36. Upon the movement of the control plate 52, to the left, as disclosed above, the cam surface 65 of the plate will cam the roller 61 and the arm member 58in a counter-clockwise direction, thus removing the shoulder 62 of the arm from a blocking position with the detent 36, thereby releasing the detent for movement. Upon depression of one of the control keys 26, 27, the hook portion 34 of the depressed key will cam the detent 36 to the right against the action of the spring 41. The spring will then move the detent to the left behind the hook portion of the depressed key, thus locking the key in its depressed position. If the other control key is depressed at this time, the camrning of the detent 36 to the right by the key being depressed will release the previously depressed key to the action of its spring 32 which will return the key to its home position. Thus only one key can be locked in its depressed position by the detent 36 during this initial phase of the machine operation.

If .the lock cylinder 30 is rotated back to its home position, the arm 58 will be rotated clockwise by the action of its spring 63 resulting in the positioning of its shoulder portion 62 in a blocking engagement with the detent 36. This operation will lock the depressed key in its depressed position, and will prevent any other control key from being depressed at this time. If the lock cylinder 30 is rotated 90 degrees counter-clockwise, as viewed in'FIG. 3, the control plate 52 will move a predetermined distance to the left which is greater than when the cylinder was rotated clockwise as described in the example previously cited. This leftward movement of the control plate 52 will position the detent 44 to condition only the control key 28 for operation. The reset key 28 when operated will be locked in its depressed condition by the locking detent 36 in the same manner as described with respect to the control keys 26 and 27. Thus it will be seen that the selection of the control key to be depressed is conditioned on the direction of rotation of the lock cylinder 30. Again if the lock cylinder is rotated back to its home position after a control key has been depressed, the detent 36 will be locked in its position by the shoulder portion 62 of the arm 58, in the manner as described above, thereby locking the depressed control key in its operated position.

Upon operation of the machine, the solenoid 81 will be energized and the solenoid 74 will be de-energized. Energizing of the solenoid 81 will rock the armature in a clockwise direction resulting in the counterclockwise rotation of the latch member 77. This movement of the latch member will release the bell crank 60 to the action of the spring 67, thus moving the shoulder 66 into a blocking engagement with the locking detent 36. This action will assure that the depressed control key will remain depressed during a machine operation.

Upon completion of the machine operation, the solenoid 74 is energized which action will rotate the armature 73 clockwise. This movement of the armature will rotate the bell crank 60 counter-clockwise which is then latched by the latch member 77, under the action of the spring 82. At this time, the solenoid 81 has been de-energized. If the lock cylinder 30 has been turned clockwise or counter-clockwise, at this time, the latching of the bell crank 60 will allow the operator to depress a control key which action will move the locking detent 36 to the right to release the previously depressed control key. If the lock cylinder 30 had been returned to its neutral position after the control keys had been depressed, the locking detent 36 would be held at this time, by the arm 58, thus locking the depressed key in position. This condition requires the operator to move the lock cylinder either clockwise or counter-clockwise before a new control keycan be depressed.

It will be seen from this construction that operation of the control keys is, dependent upon the direction of the rotation of the lock cylinder and once the machine operation has commenced, the control key that has been depressed will be locked in position, thus preventing any other control key from being used.

What is claimed is:

1. In an accounting machine having a plurality of control keys for controlling, when actuated, a machine operation, means for selectively enabling a predetermined number of control keys for actuation including a. blocking means slidably mounted adjacent said control keys for disabling the control keys from actuation, said blocking means adapted for movement to a first position releasing a first number of control keys for actuation and to a second position releasing a second number of control keys for actuation; and i b. a key-operated rotatably mounted locking means engaging said blocking means and adapted, where rotated in one direction, to move said blocking means to said-first position and when rotated in the opposite direction, to move said blocking means to said second position whereby a predetermined number of control keys are released for actuation.

2. The accounting machine of claim 1 in which said locking means includes a. a rotatably mounted key operated lock cylinder adapted for rotation in opposite directions;

b. a drive member slidably mounted adjacent said lock cylinder and engaging said blocking means;

c. and means mounted on said lock cylinder engaging said drive member and adapted, upon rotation of said lock cylinder in opposite directions, to move said drive member to two different positions whereby said blocking means is selectively moved to said first and second position.

3. The accounting machine of claim 2 in which a. said drive member includes an arcuate slot, and

b. said engaging means comprises a stud member positioned within said arcuate slot whereby upon rotation of said locking cylinder in opposite directions, said drive member is moved to two different positions. 1

4. The accounting machine of claim 3 which includes a normally disabled locking member slidably mounted adjacent each of said control keys and adapted, when released, to lock a control key in an actuated position, said locking member engaging said drive member whereby upon movement of said drive member, said locking member is released for operation.

5. In an accounting machine having a plurality of control keys for controlling, when actuated, a machine operation, means for selectively enabling a predetermined number of control keys for actuation including a. a first blocking member slidably mounted adjacent said control keys for normally disabling the control keys from actuation, said blocking member adapted for movement to a first position releasing a first number of control keys for actuation and to a second position releasing a second number 0 control keys for actuation;

b. a normally disabled locking member slidably mounted adjacent the control keys and adapted, when released, to lock a control key in an actuated position;

c. movable drive means engaging said first blocking member and said locking member and adapted, when actuated, to release said locking member for operation and to move said first blocking member to either of said first and second positions;

d. a key-operated,'rotatably mounted lock cylinder engaging said drive means, said lock cylinder adapted, when rotated in one direction to actuate said drive means whereby said first blocking member is moved to said first position, and when rotated in an opposite direction, said blocking member is moved to said second position;

. a second blocking member engaging said locking member for holding said locking member in a disabled position;

f. and first control means engaging said second blocking means and adapted, upon completion of a machine operation, to disable said second blocking member whereby upon rotation of said lock cylinder, an actuated control key is locked in its actuated position.

v 6. The accounting machine of claim 5 which includes second control means'engaging said second blocking member and adapted, upon initiation of a machine operation, to move said second blocking member to a position holding said locking member in a disabled position during a machine operation, whereby a control key is held in its actuated position during a machine operation.

7. The accounting machine of claim 5 in which said drive means includes a. a slidable mounted drive member engaging said first blocking member;

b. an arm member rotatably mounted adjacent to and engaging said drive member and adapted for movement to a position holding said locking member in a disabled position;

means engaging said' arm member for normally urging the arm member to said holding position;

. and means interconnecting said lock cylinder and said drive member whereby upon rotation of said lock cylinder, said drive member is moved to position said first blocking member to said first or second position and to rotate said arm member against the action of said urging means to a position releasing said locking member for operation.

8. The accounting machine of claim 5 in which said second blocking member comprises a. a rotatably mounted bellcrank having a blocking portion positioned adjacent said locking member;

. means engaging said bellcrank for normally urging the bellcrank in a direction whereby the blocking portion is moved into engagement with the locking member, thereby blocking movement of the locking member;

. and said first control means includes a first electromagnetic actuating member engaging said bellcrank, and adapted, upon operation at the end of a machine operation, to rotate said bellcrank whereby the blocking portion is disengaged from said locking member.

. The accounting machine of claim 8 which includes a latch member rotatably mounted adjacent said bellcrank;

b. and means engaging said latch member and adapted, upon movement of said bellcrank by said electromagnetic actuating means, to rotate said latch member to a position latching said bellcrank whereby the blocking portion of said bellcrank is disabled from a blocking position with said locking member.

10. The accounting machine of claim 9 which includes a second electromagnetic actuating member engaging said latch member and adapted, when operated at the start of a machine operation, to rotate said latch member thereby releasing said bellcrank whereby the bellcrank is moved by said urging means in a direction to position the blocking portion of the bellcrank in blocking engagement with said locking member.

. ll.v In an accounting machine having a plurality of control keys for controlling, when actuated, a machine operation, means for selectively controlling the actuation of the control keys including a. a first detent member slidably mounted adjacent said control keys for normally disabling the control keys from actuation, said first detent member adapted for movement to a first position thereby releasing a first number of control keys for actuation and to a second position thereby releasing a second number of control keys for actuation;

b. first resilient means engaging said first detent member for normally urging said detent member toward a position disabling the control keys from actuation;

c. a second detent member slidably mounted adjacent said control keys and adapted, when released, to lock'a control key in an actuated position;

(1. a blocking arm rotatably mounted adjacent the second detent member;

e. second resilient means engaging said blocking arm and adapted to move said arm to a position disabling the release of said second detent member;

f. a bellcrank member rotatably mounted adjacent said second detent member, said bellcrank member having a blocking portion positioned adjacent said second detent member;

g. third resilient means engaging said bellcrank member and adapted to move said bellcrank to a position whereby the blocking portion disables the movement of said second detent member;

h. a slidable mounted drive member engaging said first detent member and said blocking arm and adapted, when actuated, to rotate said arm to release said second detent member and to move said first detent member to either of said first and second positions;

e. a rotatably mounted key operated lock cylinder engaging. said drive member and adapted, when rotated in one direction, to actuate said drive member to position said first detent member in said first position and when rotated in the opposite direction to position said first detent member in said second position;

j. an actuating member engaging said bellcrank member and adapted, when operated, to rotate said bellcrank member to a position whereby the blocking portion of said bellcrank member is positioned to release said second detent member; and a firstelectromagnetic operating member engaging said actuating member and adapted to operate said actuating member at the end of a machine operation whereby upon rotation of said lock cylinder, after a machine operation has ended, a predetermined control key will be locked in an actuated position.

12. The accounting machine of claim 11 which includes a. a latch member rotatably mounted adjacent said bellcrank member;

b. and a fourth resilient means engaging said latch member and adapted, upon movement of said bellcrank member by said actuating member, to rotate said latch member to a position latching said bellcrank member whereby the blocking portion of said bellcrank is held in a position releasing said second detent member.

13. The accounting machine of claim 12 which includes a. a second actuating member engaging said latch member and adapted, when operated, to rotate said latch member thereby releasing said bellcrank member to the action of said third resilient means;

b. and a second electromagnetic operating member engaging said second actuating member and adapted to operate said second actuating member at the start of a machine operation whereby said second detent member is disabled from being released during a machine operation. 

1. In an accounting machine having a plurality of control keys for controlling, when actuated, a machine operation, means for selectively enabling a predetermined number of control keys for actuation including a. blocking means slidably mounted adjacent said control keys for disabling the control keys from actuation, said blocking means adapted for movement to a first position releasing a first number of control keys for actuation and to a second position releasing a second number of control keys for actuation; and b. a key-operated rotatably mounted locking means engaging said blocking means and adapted, where rotated in one direction, to move said blocking means to said first position and when rotated in the opposite direction, to move said blocking means to said second position whereby a predetermined number of control keys are released for actuation.
 2. The accounting machine of claim 1 in which said locking means includes a. a rotatably mounted key operated lock cylinder adapted for rotation in opposite directions; b. a drive member slidably mounted adjacent said lock cylinder and engaging said blocking means; c. and means mounted on said lock cylinder engaging said drive member and adapted, upon rotation of said lock cylinder in opposite directions, to move said drive member to two different positions whEreby said blocking means is selectively moved to said first and second position.
 3. The accounting machine of claim 2 in which a. said drive member includes an arcuate slot, and b. said engaging means comprises a stud member positioned within said arcuate slot whereby upon rotation of said locking cylinder in opposite directions, said drive member is moved to two different positions.
 4. The accounting machine of claim 3 which includes a normally disabled locking member slidably mounted adjacent each of said control keys and adapted, when released, to lock a control key in an actuated position, said locking member engaging said drive member whereby upon movement of said drive member, said locking member is released for operation.
 5. In an accounting machine having a plurality of control keys for controlling, when actuated, a machine operation, means for selectively enabling a predetermined number of control keys for actuation including a. a first blocking member slidably mounted adjacent said control keys for normally disabling the control keys from actuation, said blocking member adapted for movement to a first position releasing a first number of control keys for actuation and to a second position releasing a second number of control keys for actuation; b. a normally disabled locking member slidably mounted adjacent the control keys and adapted, when released, to lock a control key in an actuated position; c. movable drive means engaging said first blocking member and said locking member and adapted, when actuated, to release said locking member for operation and to move said first blocking member to either of said first and second positions; d. a key-operated, rotatably mounted lock cylinder engaging said drive means, said lock cylinder adapted, when rotated in one direction to actuate said drive means whereby said first blocking member is moved to said first position, and when rotated in an opposite direction, said blocking member is moved to said second position; e. a second blocking member engaging said locking member for holding said locking member in a disabled position; f. and first control means engaging said second blocking means and adapted, upon completion of a machine operation, to disable said second blocking member whereby upon rotation of said lock cylinder, an actuated control key is locked in its actuated position.
 6. The accounting machine of claim 5 which includes second control means engaging said second blocking member and adapted, upon initiation of a machine operation, to move said second blocking member to a position holding said locking member in a disabled position during a machine operation, whereby a control key is held in its actuated position during a machine operation.
 7. The accounting machine of claim 5 in which said drive means includes a. a slidable mounted drive member engaging said first blocking member; b. an arm member rotatably mounted adjacent to and engaging said drive member and adapted for movement to a position holding said locking member in a disabled position; c. means engaging said arm member for normally urging the arm member to said holding position; d. and means interconnecting said lock cylinder and said drive member whereby upon rotation of said lock cylinder, said drive member is moved to position said first blocking member to said first or second position and to rotate said arm member against the action of said urging means to a position releasing said locking member for operation.
 8. The accounting machine of claim 5 in which said second blocking member comprises a. a rotatably mounted bellcrank having a blocking portion positioned adjacent said locking member; b. means engaging said bellcrank for normally urging the bellcrank in a direction whereby the blocking portion is moved into engagement with the locking member, thereby blocking movement of the locking member; c. and said first control means includes a first elecTromagnetic actuating member engaging said bellcrank, and adapted, upon operation at the end of a machine operation, to rotate said bellcrank whereby the blocking portion is disengaged from said locking member.
 9. The accounting machine of claim 8 which includes a. a latch member rotatably mounted adjacent said bellcrank; b. and means engaging said latch member and adapted, upon movement of said bellcrank by said electromagnetic actuating means, to rotate said latch member to a position latching said bellcrank whereby the blocking portion of said bellcrank is disabled from a blocking position with said locking member.
 10. The accounting machine of claim 9 which includes a second electromagnetic actuating member engaging said latch member and adapted, when operated at the start of a machine operation, to rotate said latch member thereby releasing said bellcrank whereby the bellcrank is moved by said urging means in a direction to position the blocking portion of the bellcrank in blocking engagement with said locking member.
 11. In an accounting machine having a plurality of control keys for controlling, when actuated, a machine operation, means for selectively controlling the actuation of the control keys including a. a first detent member slidably mounted adjacent said control keys for normally disabling the control keys from actuation, said first detent member adapted for movement to a first position thereby releasing a first number of control keys for actuation and to a second position thereby releasing a second number of control keys for actuation; b. first resilient means engaging said first detent member for normally urging said detent member toward a position disabling the control keys from actuation; c. a second detent member slidably mounted adjacent said control keys and adapted, when released, to lock a control key in an actuated position; d. a blocking arm rotatably mounted adjacent the second detent member; e. second resilient means engaging said blocking arm and adapted to move said arm to a position disabling the release of said second detent member; f. a bellcrank member rotatably mounted adjacent said second detent member, said bellcrank member having a blocking portion positioned adjacent said second detent member; g. third resilient means engaging said bellcrank member and adapted to move said bellcrank to a position whereby the blocking portion disables the movement of said second detent member; h. a slidable mounted drive member engaging said first detent member and said blocking arm and adapted, when actuated, to rotate said arm to release said second detent member and to move said first detent member to either of said first and second positions; e. a rotatably mounted key operated lock cylinder engaging said drive member and adapted, when rotated in one direction, to actuate said drive member to position said first detent member in said first position and when rotated in the opposite direction to position said first detent member in said second position; j. an actuating member engaging said bellcrank member and adapted, when operated, to rotate said bellcrank member to a position whereby the blocking portion of said bellcrank member is positioned to release said second detent member; k. and a first electromagnetic operating member engaging said actuating member and adapted to operate said actuating member at the end of a machine operation whereby upon rotation of said lock cylinder, after a machine operation has ended, a predetermined control key will be locked in an actuated position.
 12. The accounting machine of claim 11 which includes a. a latch member rotatably mounted adjacent said bellcrank member; b. and a fourth resilient means engaging said latch member and adapted, upon movement of said bellcrank member by said actuating member, to rotate said latch member to a position latching said bellcrank member whereby the blocking portion of said bellcrank is Held in a position releasing said second detent member.
 13. The accounting machine of claim 12 which includes a. a second actuating member engaging said latch member and adapted, when operated, to rotate said latch member thereby releasing said bellcrank member to the action of said third resilient means; b. and a second electromagnetic operating member engaging said second actuating member and adapted to operate said second actuating member at the start of a machine operation whereby said second detent member is disabled from being released during a machine operation. 